1. Field of the Invention
The present invention relates to an improved aerial work apparatus which provides greater elevation while maintaining improved stability.
2. Description of the Related Art
Aerial work apparatuses are used for a variety of purposes, such as repairs, construction, or other operations where it is necessary to elevate a worker. Many devices of this type are known in the prior art. U.S. Pat. No. 4,280,589 discloses a device having a multi-part mast and an extensible boom, all of these parts being operated by hydraulic cylinders. U.S. Pat. No. 4,133,411 teaches an extensible boom mounted on a moveable vehicle base. In U.S. Pat. No. 3,767,007 an extendable ladder is mounted on a turret. A method of driving a rotatable base plate by cylinders and a sprocket is shown in U.S. Pat. No. 3,179,267.
U.S. Pat. No. 4,511,015 teaches an aerial work apparatus with improved stability comprising a wheeled chassis; an aerial platform; a rotating base having a center line of rotation mounted on the wheeled chassis; a fully hydraulic, telescoping main vertical mast mounted on the rotating base plate slightly offset from the center line of rotation of the base plate in a direction opposite to the position of the aerial platform, which main vertical mast includes at least two telescoping sections, the lower section being smaller in cross-section than the next adjacent higher section, which sections are driven to reciprocate by a package of cylinders located within the innermost telescoping section so as to be removable therefrom without disassembly of the telescoping sections, and a telescoping boom mounted on one side of the uppermost section of the vertical mast and extending beyond the other side of said mast in a straddling manner to the aerial platform, said telescoping boom being operated by hydraulic cylinders located substantially on the one side of said vertical mast opposite the position of the aerial platform.